I have heard nothing further at present from Mr. Rochford about his Heterodera experiments. I think I must remind him soon that he kindly promised me a report.
1, Cluster of eggs; 2, egg, magnified; 3, grub, magnified; 4, line showing natural length; 5 and 6, pupæ; 7 and 8, 2-spotted lady-bird, Coccinella bipunctata, L. (= dispar), and dark variety; 9, 7-spotted lady-bird, C. septempunctata, L., like in form but much larger than the black lady-bird.
FIG. 59.—LADY-BIRDS, COCCINELLIDÆ.
1, Geophilus longicornis; 2, Lithobius forficatus, “thirty-foot”; 3, head of Lithobius forficatus, magnified.
FIG. 60.—LONG-HORNED CENTIPEDES.
May 14, 1894.
I have been quite sorry for a long time that I have had no specimens which would be of interest to you. I was afraid you might think I was not attending to these subjects, but now I have received a cucumber root quite beset with galls, of which I forward you a portion. It is from a nursery gardener at Rhyl, in Flintshire, North Wales, where they are much troubled by cucumber and tomato plants dying, some of both kinds having the “roots covered with galls but some have not.” Messrs. Maxwell and Dalgliesh sent me some of the roots without galls, from plants that were nearly dead, but I could not discover the cause of the failure of these. On such inefficient examination as I make, I find in the soft pulpy centre of the larger galls some anguilliform nematodes, which I conjecture to be males, or larvæ, of the H. radicicola, but so far as I searched I did not find females; there were a fair number of eggs. On cutting the pieces of plant into fragments for packing I find the stem just about the ground-level much beset with diseased growth. I have not, however, delayed to try to examine this, for I might be only wasting specimens. Messrs. M. and D. have five houses fifty yards long each, so the infestation is a serious trouble to them. They tell me that they clear out all the soil each year, and bring fresh soil in. It “is rich alluvial soil.” They have tried lime, soot, and nitrate of soda without effect, and I should certainly say that something requires alteration for the extermination even of an infestation much more easily dealt with; for they are troubled by millepedes (fig. [27]), and also there are such great numbers of Geophilus (centipedes), that there must, I think, be something amiss whether these live chiefly on vegetable matter or on small animal vermin.
Some inquiry about H. radicicola has been sent to me from Glen St. Mary, Florida, U.S.A., but no new information.
On Saturday, Professor Ainsworth-Davis wrote to ask me to write a preface to his translation of your “Zoologie,” and it will gratify me very much indeed to prepare such a one as I hope may please you. Your book will be a very valuable addition to our educational series, and I shall like very much to be permitted thus to appear in colleagueship.
October 3, 1894.